Really SLOW acceleration under D

darkzebra · 02-08-2006, 04:45 PM

I just bought a 1988 Supra Turbo for my 16 year old son.

The car seems to have one mechanical(?) problem: it accelerates normal under R, L, 2, but creeps (really creeks) under D

Motor sounds fine during idle. There is no overheating or apparent head gasket problem.

XtreeX · 02-08-2006, 09:21 PM

I'm having the same problem with my 1990 N/A Supra. Feels like I'm giving it tons of gas but it's just not moving. Granted it's not a turbo, but still...

I took it in to have the timing belt checked out and they said it was fine. Next step is just having the catalytic converter looked at, it sounds groggly... So it it's jammed up inside then I'm just going with a all new exhaust (straight pipe).

Anyone have any ideas what else it would be? HG is fine and all pumps are in working condition, no leaks, all hoses replaced.

mrnickleye · 02-08-2006, 11:46 PM

Either take it to a shop and have the EXHAUST back pressure tested, or unbolt the exhaust pipe from the manifold and drive it to see if it improves. A plugged exhaust can give a NO power situation.

rnoswal · 02-10-2006, 04:42 AM

Sounds more like a transmission problem than engine, especially if it runs fine in the other gears.

Russ

darkzebra · 02-11-2006, 03:30 AM

I thought about tranny, but I can't understand why it would work normal in L and 2, and not in D.

Isn't L and 2 the same physical 1st and 2nd gears under D?

rnoswal · 02-11-2006, 04:40 AM

Well your selector may be out of adjustment and for some reason not starting out in 1st gear when put in D. Or it might be an internal problem. But if it runs pretty good in the other two gears then I would count out the engine as being a problem.

Russ

mrnickleye · 02-11-2006, 11:49 PM

When you drive the car in 1st or 2nd, if you can rev up to 5k rpm for a few seconds, then the exhaust is not likely clogged. Also, if it does this smoothly, without misfires and stumbles, then the ignition and fuel system are likely ok.

So...if it seems sluggish in D (drive), then likely the transmission is starting out in 2nd or 3rd.

That would be likely be either a ETC (electronic Transmission Control) computer, or shift solenoid problem. It can be diagnosed by a reputable tranny repair shop. There is a very good chance that it can be repair without a complete overhaul.

The problem for you also is....finding a shop/technician that KNOWS how to diagnose. Most just want to rebuild, figuring that it will get fixed along the way.

The same is true with engine electronic problems. Finding a KNOWLEDGABLE tech can be frustrating, and costly.

ComptonsF1NEST · 02-12-2006, 04:51 AM

i know in Hondas some of the Shift soleniods in the auto trannys will go bad and make the trans skip gears and do weird stuff.

take it back and buy a 5 speed

XtreeX · 02-12-2006, 05:21 AM

Taking it back isn't the answer, I like having an automatic. For my car, the acceleration isn't abysmal, just a little slow. I'm going to get a new exhaust and we'll see if that fixed it. If not, then I'll have to look deeper in the transmission.

rnoswal · 02-12-2006, 05:37 AM

I was just curious about something. If the car accelerates normally in R, 1 and 2 but not in D, what happens if you start the car off in D and it starts its creeping, then you pull the shifter back to 1, does it accelerate normally, quickly again? And if you put it in 2, does it shift twice or just start in 2nd and stay there?

Russ

02-08-2006, 04:45 PM	#1
darkzebra Stock Join Date: Feb 2006 Posts: 4	Really SLOW acceleration under D I just bought a 1988 Supra Turbo for my 16 year old son. The car seems to have one mechanical(?) problem: it accelerates normal under R, L, 2, but creeps (really creeks) under D Motor sounds fine during idle. There is no overheating or apparent head gasket problem.

02-08-2006, 11:46 PM	#3
mrnickleye 1000whp postwhore Join Date: Jun 2005 Location: Mojave Desert, Calif. Posts: 1,705	Either take it to a shop and have the EXHAUST back pressure tested, or unbolt the exhaust pipe from the manifold and drive it to see if it improves. A plugged exhaust can give a NO power situation. __________________ Had a Red 1989 N/A. Automatic. Sports Pkg. w/wing. TEMS, and some nice MODS. Sold to a friend 10/08/08.

02-11-2006, 03:30 AM	#5
darkzebra Stock Join Date: Feb 2006 Posts: 4	Really SLOW acceleration under D I thought about tranny, but I can't understand why it would work normal in L and 2, and not in D. Isn't L and 2 the same physical 1st and 2nd gears under D?

02-11-2006, 11:49 PM	#7
mrnickleye 1000whp postwhore Join Date: Jun 2005 Location: Mojave Desert, Calif. Posts: 1,705	When you drive the car in 1st or 2nd, if you can rev up to 5k rpm for a few seconds, then the exhaust is not likely clogged. Also, if it does this smoothly, without misfires and stumbles, then the ignition and fuel system are likely ok. So...if it seems sluggish in D (drive), then likely the transmission is starting out in 2nd or 3rd. That would be likely be either a ETC (electronic Transmission Control) computer, or shift solenoid problem. It can be diagnosed by a reputable tranny repair shop. There is a very good chance that it can be repair without a complete overhaul. The problem for you also is....finding a shop/technician that KNOWS how to diagnose. Most just want to rebuild, figuring that it will get fixed along the way. The same is true with engine electronic problems. Finding a KNOWLEDGABLE tech can be frustrating, and costly. __________________ Had a Red 1989 N/A. Automatic. Sports Pkg. w/wing. TEMS, and some nice MODS. Sold to a friend 10/08/08.

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02-08-2006, 09:21 PM	#2
XtreeX 3" Exhaust Join Date: Feb 2006 Location: Rockford, IL Posts: 92	I'm having the same problem with my 1990 N/A Supra. Feels like I'm giving it tons of gas but it's just not moving. Granted it's not a turbo, but still... I took it in to have the timing belt checked out and they said it was fine. Next step is just having the catalytic converter looked at, it sounds groggly... So it it's jammed up inside then I'm just going with a all new exhaust (straight pipe). Anyone have any ideas what else it would be? HG is fine and all pumps are in working condition, no leaks, all hoses replaced.

02-10-2006, 04:42 AM	#4
rnoswal Lexus & 550's Join Date: Apr 2005 Location: Bossier City LA Posts: 556	Sounds more like a transmission problem than engine, especially if it runs fine in the other gears. Russ

02-11-2006, 04:40 AM	#6
rnoswal Lexus & 550's Join Date: Apr 2005 Location: Bossier City LA Posts: 556	Well your selector may be out of adjustment and for some reason not starting out in 1st gear when put in D. Or it might be an internal problem. But if it runs pretty good in the other two gears then I would count out the engine as being a problem. Russ

02-12-2006, 04:51 AM	#8
ComptonsF1NEST Stock Join Date: Feb 2006 Posts: 3	i know in Hondas some of the Shift soleniods in the auto trannys will go bad and make the trans skip gears and do weird stuff. take it back and buy a 5 speed

02-12-2006, 05:21 AM	#9
XtreeX 3" Exhaust Join Date: Feb 2006 Location: Rockford, IL Posts: 92	Taking it back isn't the answer, I like having an automatic. For my car, the acceleration isn't abysmal, just a little slow. I'm going to get a new exhaust and we'll see if that fixed it. If not, then I'll have to look deeper in the transmission.

02-12-2006, 05:37 AM	#10
rnoswal Lexus & 550's Join Date: Apr 2005 Location: Bossier City LA Posts: 556	I was just curious about something. If the car accelerates normally in R, 1 and 2 but not in D, what happens if you start the car off in D and it starts its creeping, then you pull the shifter back to 1, does it accelerate normally, quickly again? And if you put it in 2, does it shift twice or just start in 2nd and stay there? Russ